1. Field of the Invention
The invention relates to a thermoplastic composition having improved properties such as impact strength. It particularly relates to blends of polypropylene with a copolymer of styrene and maleic anhydride, an elastomeric EPM or EPDM which has been modified with specified functional groups, and a polypropylene modified with specified functional groups.
2. Description of Information Disclosures
Various blends of thermoplastics and elastomers are known.
U. S. Pat. No. 4,742,116 discloses a thermoplastic moulding composition comprising a mixture of (A) copolymer of styrene and/or alpha methylstyrene and maleic anhydride, and (B) an ethylene-propylene modified rubber or an ethylene-propylene-diene modified rubber, said rubber having been modified by grafting thereto a compound containing hydroxyl, amide or amine groups.
European Publication 0140422-Al published May 8, 1985 (European patent application 842013807 filed Sep. 27, 1984) discloses a process for preparing a thermoplastic moulding composition by mixing styrene and/or methylstyrene, maleic anhydride with a rubber modified with hydroxyl groups (e. g. EP or EPDM rubber), in the presence of a specified amount of reaction accelerator such as an organic compound of a metal of groups II, III and IV of the Periodic Table of Elements.
U. S. Pat. No. 3,856,765 discloses copolymers of ethylene, propylene, with or without a diene, and functional monomer which may be a 2-substituted-5-norbornene.
European Patent Publication 0321293 published Jun. 21, 1989 (European Patent Application 88311965-3 filed Dec. 16, 1988) discloses improved polybutylene terephthalate moulding composition comprising a minor amount of a copolymer of ethylene, a higher alpha olefin, optionally a polymerizable non-conjugated diene, and a 2-substituted-5-norbornene in which the 5-norbornene substituent may be carboxyl, hydroxyalkyl, amino, N-aminoalkyl or N-aminoaryl.
U.S. Pat. No. 4,987,200 discloses ethylene-propylene elastomers comprising a 2-substituted-5-norbornene monomer.
U.S. Pat. No. 4,251,644 discloses blends of modified EPM or modified EPDM polymers with polyesters such as dacron or polyamides such as nylon. The modified EPM or EPDM incorporates highly polar groups such as amine groups, amide groups, thio groups, ethepaopoups, and ester groups.
U.S. Pat. No. 4,663,989 and U.S. Pat. No. 4,569,969 disclose a moulding composition comprising (a) styrene maleic anhydride-methyl methacrylate terpolymer which contains a rubber component (optional in U.S. Pat. No. 4,569,969), (b) an ABS or MBS polymer, and (c) polycarbonate resin. The polyblend exhibits a marked increase in Izod impact over a similar polyblend without the termonomer component of (a).
U.S. Pat. No. 4,491,647 discloses a polyblend comprising a thermoplastic PC and at least one copolymer selected from methylmethacrylate/n-phenylmaleimide and EPDM-g-methylmethacrylate/n-phenylmaleimide. In one embodiment, the polyblend consists of an ABS resin and/or a rubber modified SMA.
U.S. Pat. No. 4,469,843 discloses a moulding composition of a rubber modified SMA non-equimolar copolymer and a PC resin. The rubber is a conjugated diene-styrenic copolymer containing 65 wt. % or more of conjugated diene.
U.S. Pat. No. 4,456,732 discloses a blend of PC, rubber modified SMA and an epoxy resin. The thermoplastic resin composition has improved weld strength.
U.S. Pat. No. 4,367,310 discloses a blend of bisphenol-A type polycarbonate with (1) a grafted and non-grafted rubber, such as diene rubber or a diene rubber grafted with a polar polymer (2) SMA and (3) a compatible polymer such as styrene acrylonitrile (SAN). These blends exhibit improved impact strength, melt flow and heat resistance. A typical example of such a blend is one consisting of PC, SMA, ABS resins (containing grafted and non-grafted butadiene rubber) and SAN.
U.S. Pat. No. 4,351,920 discloses a thermoplastic resin composition containing (a) 5 to 40 wt. % of a rubber modified SMA and (b) 95 to 60% of a PC resin as main components.
U.S. Pat. No. 4,386,187 and U.S. Pat. No. 4,386,188 disclose a polymer blend comprising a polyolefin such as polyethylene or polypropylene as major component, a styrene polymer which may be a styrene-maleic acid copolymer, and a styrene-butadiene-styrene block copolymer compatibilizer.
U.S. Pat. No. 4,753,997 discloses a method of grafting maleic anhydride or maleic acid styrene onto polyolefins such as propylene polymers by mixing maleic anhydride, a free radical initiator comprising an organic peroxide, a polyolefin, and a catalyst, such as a N,N-dialkylethanol-amine and heating the mixture to an elevated temperature.
Japanese Patent Publication 237943 published Aug. 28, 1990 (early publication dated Mar. 28, 1983) discloses a polypropylene composition containing a polypropylene component, an elastomeric copolymer of ethylene and propylene and a modified polyethylene component having as modifying group an amino group, a secondary amino group, a tertiary amino group, a hydroxyl group, a tri (hydrocarbyloxy) silyl group, or an oxysilaryl group.
U.S. Pat. No. 4,968,747 discloses a thermoplastic resin composition containing a crystalline polypropylene component, an elastomeric olefin polymer, random styrenic copolymers and epoxy group-containing copolymers. A two-step blending process for producing the disclosed resins is also discussed.
Although the known blends of thermoplastic polymers and elastomers have some improved properties, there is still a need to improve the properties of thermoplastic polymers, such as, for example, polypropylene.
It has now been found that properties, such as impact strength, of thermoplastic blends, such as a blend of a copolymer of styrene and maleic anhydride with polypropylene, can be improved by blending them with an elastomeric EP or EPDM which has been modified by specified functional groups and a polypropylene modified with specified functional groups.